Baler and method of baling

ABSTRACT

A baler apparatus includes a baling chamber including at least one adjustable wall for adjusting compression of a body of bale material. A reciprocating plunger is operable to compress the bale material and a binding device binds the compressed material to form a bale by use of twine loops. An adjustment mechanism increases as a length of outer twine loops when binding the bale relative to the inner twine loops, to reduce compression within part of the body of bale material and avoid twine breakage that can otherwise occur as a bale is ejected from the baler.

The present invention relates to a baler and a method of baling, inparticular but not exclusively for baling an agricultural crop.

BACKGROUND TO THE INVENTION

For efficient transport and storage, and to improve the keepingproperties of the product, agricultural products like hay, straw andsilage may be compressed into bales of a parallelepiped shape, which areknown as ‘square’ bales. After the compression of the bale material theshape and the compression of the bale is maintained by binding the balewith twines that are looped around the compressed bale material. Theends of the twine are then knotted together.

Typically, compression of the bale material is performed by areciprocating plunger press baler. A typical baler of this type isdescribed in U.S. Pat. Nos. 4,074,623 and 4,142,746 to HesstonCorporation. This baler machine includes a baling chamber comprising anopen-ended channel through which bale material is forced by areciprocating plunger. The plunger is driven in a substantially lineardirection between two end positions comprising respectively a withdrawnposition in front of the baling chamber and an extended position inwhich it extends into the baling chamber. When the plunger is in thewithdrawn position the baling chamber is loaded with the bale materialto be compressed. The plunger is then driven into the baling chamber sothat this new material is compressed against a body of compressedmaterial already in the baling chamber. Any newly compacted materialthat is added to the already compacted material in the chamber is calleda ‘wad’. The friction of the compressed material with the walls of thebaling chamber provides a resistive force allowing for compression ofthe new material that is introduced into the baling chamber in front ofthe plunger.

After compression, the newly compressed material and the compressedmaterial already in the baling chamber are moved together towards theoutlet end of the channel until the plunger reaches its fully extendedend position. The plunger then moves in the opposite direction towardits withdrawn position so that the baling chamber can be reloaded withnew material to be compressed.

The friction within the baling chamber between the already formed baleand the walls of the channel can be regulated for instance by pressingthe side walls and/or the top panels of the baling chamber against thecompressed material with different levels of force.

The bale is held in compression after leaving the machine by binding thebale with twines that are tied around the body of compressed material.In some machines, a single spool process is used in which each bindingis formed with twine that is taken from a single spool and looped aroundthe entire circumference of the bale, then tied with a single knot. Sucha process is described in U.S. Pat. No. 3,895,571, which includes amechanism for releasing the tension in the twine during knotting so asto avoid problems while knotting the twine.

Another example of a machine that uses a single spool process isdescribed in EP0392627A. This machine includes a mechanism for reducingthe bale pressure at the start of the bale forming process to allow thebinding twine to slide more easily between the bale material and thepreviously formed bale that is still in the baling chamber.

Another machine that uses a single spool process is described inDE4031695A. This machine includes a mechanism for reducing the balepressure at the start of the twine knotting process to allow the bindingtwine to be knotted more easily.

Other baling machines use a twin spool process in which each binding isformed using twines from two spools, which are tied with two knots atopposite ends of the bale. One advantage of the twin spool process isthat the bale can be compressed to a higher compaction pressure becausethe twine does not have to be passed between the newly compacted baleand the previously formed bale. However, this increased compactingpressure also increases the risk of the twines breaking when the bale isejected from the baling chamber. The twin spool binding process will nowbe described in more detail.

At the start of the baling process two lengths of twine from spools onopposite sides of the baling chamber are connected to one another bytying the ends of the twines together.

As the bale material is compacted in the baling chamber the spools feedtwine to the baling chamber on either side of the bale material. On oneside of the baling chamber the twine passes through the tip of a balingneedle. When the body of bale material has reached its full length,between two successive compressing strokes, the needle brings the twineas a loop to the other side of the baling chamber. A knotter device thenknots the twine, joining an end of the twine loop that was broughtaround the compressed bale by the needle to an end of the twine that wassupplied by the spool on other side of the baling chamber (on the sameside as the knotter). A second knot is also formed for the start of thenext bale. The needle is then retracted and a new bale is started.

The pressure applied to the material in the baling chamber during thecompression stroke is typically 3 to 4 bar for a bale with a typicalcompression surface of 90*120 cm. The knotted twine used in this type ofbaling machine typically has a breaking strength of 200 kgf. Six knottedtwines can therefore hold about 6*2*200=2400 kgf. In a conventional balewith a compression surface of 90*120 cm this results in a holdingpressure of only 0.22 bar. This places an upper limit on the compressionpressure that can be applied to the bale. If a higher compression levelis to be maintained, more binding twines have to be used.

There is generally some expansion of the bale as it is ejected from thechannel of the baling chamber and this expansion has to be taken intoaccount when designing the baling machine to ensure that the twines areable to maintain the compression of the bale without breaking. However,the amount of expansion is not uniform. Some materials such as dry strawand grass are more elastic than others and tend to expand more. There istherefore a greater risk that the twines will break when baling suchmaterials.

To reduce the risk of breakage when baling highly elastic balematerials, in praxis the overall compression level is sometimes reduced.However, this reduces the density and mass of the bale, which isgenerally undesirable.

Alternatively, the twine loops tied around the compressed material canbe made by design slightly longer than the circumference of thecompressed bale while it is in the baling chamber. Then, when the baleleaves the baling chamber it expands to a size determined by theslightly greater length of the twine. Due to this expansion, thepressure in the bale falls to a value that can be withstood by thetwines. However, this also has a negative impact on the mass and densityof the bale and it results in a lower level of compression for allmaterials, including less elastic materials for which a lower level ofcompression is not needed.

Recently, the compression level that can be produced by baling machinesthat use the twin spool process has increased to typically about 6-10bar, but the holding strength of the twine has hardly improved. Theincreased compression level places greater stress on the baling twines,particularly when binding materials that are relatively elastic, forexample dry grass. We have found that with some materials and/or incertain weather conditions the pressure after expansion of the bale canbe higher than the twines can withstand. As a result, we have found thatthe twines can break and the bales can then burst during or afterleaving the baling chamber. Furthermore, because the twines near theedges (outermost sides) of the bale have to withstand more force due tothe fact that there is more material to hold, there is more tension onthe outer twines than on the inner twines. When bales expand too muchupon ejection the outer twines will tend to burst first, especially theouter twines.

Attempts to reduce the problem described above have been described inU.S. Pat. No. 4,577,553 which includes a mechanism for increasing thelength of the twine loops so that they are less likely to burst,particularly when using sisal twine. However this invention does notdescribe any possibility to adjust the increase of loop length inrelation to the expansion of the material. Furthermore, it iscomplicated and not reliable since the hook for pulling extra twinelength has to grab the twine from the bale, while the position of thetwine on the bale can vary widely.

Another attempt to address the problem is described in WO 2013017229. Inpraxis it shows that this method under certain field and materialconditions is difficult to adjust and gives poorly shaped bale ends andsometimes overly dense bales because the last part of the bale iscompressed at a lower level.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a baler and a method ofbaling that mitigate the problems identified above and, in particular,that allow optimum and constant compression of all bale materials andcompensate for differences in the elasticity of those materials, whilereducing the risk of twine breakage.

According to one aspect of the present invention there is provided abaler apparatus according to claim 1 including a baling chambercomprising a channel having an inlet end and an outlet end, areciprocating plunger adjacent the inlet end of the baling chamber thatis operable to compress a body of bale material within the balingchamber, and a binding device for binding the compressed body of balematerial to form a bale, wherein the baling chamber has at least oneadjustable wall for adjusting the compression of the body of balematerial by controlling the pressure applied to the body of balematerial during formation of a bale, the apparatus being furtherprovided with means for increasing the length of at least the outertwine loops, relative to the inner twine loops of the bale at binding,to reduce the tension in twines on the outer part of the body of balematerial.

By increasing the loop length of the outer twines relative to the innertwines at least just before and during the knotting process, the tensionof the outer binding twine after the bale leaves the baling chamber canbe reduced and/or equalled to the tension in the inner binding twines,thereby reducing the risk of breakage if the bound bale expands eitheron leaving the baling chamber or subsequently. Preferably the differenceof twine loop length between outer and inner twines can then becontrolled according to the nature of the bale material. For example,the difference of twine loop length can be greater if the bale is madeof relatively elastic material such as dry grass, or lower if the baleis made of less elastic material.

The bale weight and density can therefore be maintained at a high level,without increasing the risk of the bale bursting and without reducingthe compression force in the last part of the bale.

Preferably the increase of loop length in the outer twines relative tothe inner twines is formed by guiding the twine over an adjustableroller or guide at the top part of the bale, preferably near to theknotting device. Such an arrangement is a simple design with no activeelements, i.e. passive parts that have little risk of malfunctioning.

According to the invention, the increase of the individual twine loopscan be adjusted per twine loop. Particularly, the outermost twines moreto the left and right side of the bale are configured to have more looplength as these twines will have to withstand more expansion force thanthe ones in the middle of the bale. Preferably this extra loop lengthincrease is 1-3 cm relative to the inner twines.

Preferably the length of the second-most outer twine loop could beincreased to a lesser value, preferably 1-2 cm, as the outer twineloops. This to fully equal the tension of all twine loops.

Preferably the roller/guide for increasing the loop length is easilydisplaceable/removable for servicing the knotter and for re-routing thetwine after breakage of a twine.

Preferably the roller/guide for increasing the loop length is fixedlybut adjustably connected to the baler.

Preferably the increase of the loop length can be achieved bypositioning the knotting device of the outer twine loops relativelyfurther from the bale when the twine loop is formed. This arrangement isadvantageous because no extra parts are required that could obstruct thematerial flow.

According to another aspect of the invention there is provided a methodof baling bale material in a baler apparatus having a baling chamberincluding a channel with an inlet end and an outlet end, a reciprocatingplunger adjacent the inlet end of the baling chamber, and a bindingdevice, the method comprising activating the reciprocating plunger tocompress a body of bale material in the baling chamber and use of atleast one adjustable means for increasing the twine loop length of atleast the outer two twine loops relative to the inner twine loops, atleast during the closing of the loop, to form a bale. The twine looplength can be determined as a function of the bale material andassociated conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view showing the main components of a balingmachine;

FIG. 2a is a schematic illustration plan view of a prior art balingmachine during compression of the bale material;

FIG. 2b is a schematic illustration plan view of the prior art balingmachine after withdrawal of the plunger and prior to binding of the balematerial;

FIG. 3a is a schematic illustration of a prior art bale bound withbaling twine, before the ends of the twine are tied;

FIG. 3b is a schematic illustration of the prior art bale, after theends of the baling twine are tied;

FIG. 3c is a schematic illustration of the prior art bale after the balehas expanded, causing breakage of the baling twine;

FIGS. 4a to d are schematic illustration of a baling machine accordingto an embodiment of the invention during closing of the twine loop;

FIGS. 5 and 5 b shows the device incorporated in the design of a baler.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The baling machine or baler shown in FIG. 1 includes a baling chamber 2that is defined by top and bottom plates 3 and two side walls 4, one ofwhich has been omitted from the drawing to show the interior of thechamber 2. The baling chamber 2 comprises a channel having an inlet end6 and an outlet end 8. At the inlet end 6, the channel is closed by aplunger 10 that can be driven into the baling chamber 2 in areciprocating manner. In this example, the plunger 10 is driven from arotating drive axle 12 via a pair of drive arms 14, 16. The balingmachine also includes a binding device 17, for example as described inU.S. Pat. No. 4,074,623, for binding the bale with binding twine.

In addition, the baling machine includes a pick up mechanism A forpicking up cut bale material (for example grass and straw) from theground, a feed mechanism B for feeding the bale material into the balingchamber 2, a set of needles C for feeding binding twine through thebaling chamber and a drive mechanism D for transmitting drive to thedrive axle 12 from the drive output of a towing vehicle (not shown).These components are all conventional and so will not be described indetail.

The prior art baling machine represented schematically in FIGS. 2a and2b is substantially as described in U.S. Pat. No. 4,074,623, thecontents of which are understood by a skilled person and incorporatedherein by reference. The baling machine includes a baling chamber 2 thatis defined by two side walls 4, as well as by top and bottom plates (notshown in FIGS. 2a and 2b , but denoted 3 in FIG. 1). The opposed sidewalls 4 are inclined towards one another to provide a tapered channeland can be adjusted to different degrees of taper. The baling chamber 2thus consists of a channel having an inlet end 6 and an outlet end 8. Atthe inlet end 6, the channel is closed by a plunger 10 that can bedriven into the baling chamber 2 in a reciprocating manner. In thisexample, the plunger 10 is driven from a rotating drive axle 12 via apair of drive arms 14, 16.

The baling machine of FIGS. 2a and 2b is shown in operation, containingwithin the baling chamber 2 a compressed but unbound body 18 of balematerial and a compressed and bound bale 20. The completed bale 20 isbound with binding twine 22. In this example, five loops of bindingtwine 22 are used, which extend around the top, bottom, front and rearfaces of the bale 20.

In FIG. 2a the baling machine is shown during a compression stroke, inwhich the plunger 10 is driven forwards as depicted by arrows 24 intothe baling chamber 2. As a result of this movement of the plunger 10, abody 18 of bale material that has been loaded into the baling chamber 2is driven forwards within the baling chamber 2 against the end face ofthe already formed bale 20. The body 18 of bale material is thuscompressed both longitudinally and transversely: longitudinalcompression resulting from being pressed by the plunger 10 against theend face of the already formed bale 20 (and from the frictional forcesacting on the bale 20), and transverse compression of the body 18resulting from it being forced between the converging side walls 4. Thefrictional force on the body 18 of bale material can be regulated byadjusting the positions of the side walls 4 and/or the top and bottomplates as indicated by arrows 30.

During compression, the front and rear faces 25 a, 25 b of the body 18of bale material are driven forwards by the plunger 10 as depicted bythe arrows 26, 28. The resulting compression of the bale material isindicated by diagonal arrows 32. This process is repeated until the body18 of bale material has reached the required size.

Once the body 18 of bale material has reached the required size, thebale material is bound with baling twine. A set of needles (not shown inFIGS. 2a and 2b , but denoted C in FIG. 1) carrying the binding twinesare extended through slots 34 in the face of the plunger 10 and thetwines 22 are then tied around the bale. The binding and knottingprocesses may for example be substantially as described in U.S. Pat. No.4,074,623.

After the bale material has been bound, the plunger 10 withdraws asillustrated by arrows 35 in FIG. 2b so that bale material for the nextbale can be fed into the baling chamber. As the plunger withdraws, therear face 25 b of the body 18 of bale material recovers slightly andexpands a short distance rearward as depicted by arrows 36. Thisrearward expansion of the body 18 of bale material is limited by thebinding twines 22 that have been tied around the body 18 of balematerial and increases the tension in the binding twines.

The next bale is then formed by introducing bale material into the gap37 between the plunger 10 and the rear face 25 b of the bale that hasjust been formed, then compressing the material by reciprocatingmovement of the plunger 10. This process is repeated as necessary toincrease the size of the compressed body of bale material. As theprocess is repeated, the bale 20 that has just been formed is pushedalong the channel towards the downstream end 8 of the baling chamber 2,and the previously formed bale 20′ is ejected from the downstream end ofthe baling chamber 2 onto the ground.

When the bale 20′ is ejected from the baling chamber the compressiveforces acting on the front and rear faces of the bale are removed,allowing the bale 20′ to expand against the tension of binding twines22. The overall length of the bale 20′ therefore increases slightly, theunexpanded size of the bale 20′ being indicated by broken lines 38. Thisincreases the tension in the twines 22. As a result of this partialdecompression of the bale the load carried by the twines 22 as the baleis expelled from the baling chamber 2 is significantly less than thepressure that was applied to the bale material by the plunger 10 (forexample about 0.22 bar as compared to a compacting pressure of 4-10bar).

The prior art binding process is illustrated again in FIGS. 3a to 3c .In FIG. 3a , the bale 20 is shown in a compressed state, with two twines22 a, 22 b forming a loop around the bale. First ends of the twines havebeen tied together forming a first knot 40. The second ends 22 a′, 22 b′of the twines have not yet been tied together.

In FIG. 3b the bale 20 is shown after the second ends of the twines 22a, 22 b have been tied together forming a second knot 40′. An extralength L of twine is required by the knotting device, which is releasedafter the knot 40′ has been tied. Therefore, when both ends of the twineare released from the knotting device the total length of the twinebinding increases by L1+(L3−L2), which slightly reduces the tension inthe binding.

When the bale 20 is ejected from the baling chamber, both ends of thebale expand by a distance e as shown in FIG. 3c , the original positionsof the ends of the bale being depicted by broken lines 38. This causesthe circumference of the bale to increase by a length of 4*e. If theincrease in circumference is greater than the additional length of twinereleased by the knotting device, that is if 4*e>L1+(L3−L2), the overalltension in the twine binding will increase, which may result in failureof the twine forming the binding at knot 40′ or 40.

As is shown in FIG. 2b the twines most to the side of the bale (referredto herein as “outermost”) have to withstand a bigger part of theexpanding bale (½Z+X) compared to the twine loops around the middle ofthe bale (2*½Z). Therefore the tension of the outer twine loops tends tobe higher than the inner twine loops. It is observed that when breakageof the twine loops occur that in most of the cases the most outer twineswill break first. When the outer twines break the second-most outertwines will become the outer twines and will break subsequently.

A schematic baling machine according to an embodiment of the inventionis shown in FIGS. 4a and 4b . This machine is similar in many respectsto the prior art machine shown in FIGS. 1, 2 a and 2 b and the foregoingdescription therefore applies in part also to this machine. As in theprior art machine, the side walls 4 (not shown in FIGS. 4a and 4b )include adjustable wall sections, each adjustable wall section beingmounted for pivoting movement about a pivot joint at the upstream edgeof the wall section. An adjuster device is connected to each wall, theadjuster device being operable to adjust the position of the wall andthereby to adjust the frictional force applied to the already-formedbale 20 as it moves through the baling chamber 2. Alternatively or inaddition, the adjuster devices may be configured to adjust the positionsof the top and/or bottom walls of the baling chamber. The adjusterdevices may for example be hydraulically or electrically driven and arecontrolled by a control device, which can operate automatically or inresponse to control signals provided by the operator.

According to the invention, a twine loop increasing roller/guide 41 isprovided to be engageable with the outermost twine loops 22, where itcan be either fixed or adjusted to a position that increases the twineloop length by causing the binding device at that location to spool outmore twine to a desired length before a knot 40′ is tied, compared tothe innermost loops. FIGS. 4a to 4d show different possible positions soas to increase the loop length from nothing as shown in 4 a to a maximumas shown in 4 d. The roller may be fixed in any of the positions ofFIGS. 4b to 4c or adjustable between these options. Meanwhile, twineloops on the inward part of the bale can be formed in a conventionalmanner where no additional length needs to be applied.

Control over the twine loop length is preferably adjustable so as toadapt the process to the expansion properties of the bale material,where expansion affects mostly on the outermost sides. For relativelyinelastic materials that expand only slightly after compaction (e.g.silage), the required increase will be small (e.g. FIG. 4b ), whereasfor more elastic materials that tend to expand a lot after compaction(e.g. dry straw and/or materials that are baled in very dry conditions)the required increase will be substantial (e.g. 5-10 cm at compressionlevels of 6-10 bar, e.g. 4 c or 4 d).

FIGS. 5a and 5b illustrate a cross section of a loop extending mechanismaccording to the invention located at the outer edges of where a bale isto be formed. A roller 41 is arranged to move to a number of differentpositions 41′, 41″ which, in practice, causes more twine to be drawnfrom a spool (not shown) before a knot is tied to secure the twine abouta circumference of the bale 20. As mentioned, the extent of thelengthened position is determined by the material or other environmentalconditions either sensed automatically or activated by manual inputsettings.

The configuration of the invention described is intended to extend theperipheral or outermost twine loops of the bale, compared to the innertwines (e.g. of the five twine loops 22 across the bale in theillustrated prior art FIG. 2, the outermost would amount to the firstand fifth loops, whereas the third is the innermost), to the sameextended length in order to account for additional compression at theouter sides. However, the invention could be configured to providedifferent twine loop lengths across the same bale if this weredesirable. In other words a series of rollers 41 could moveindependently of one another. In the preferred form the outermost twineloops (on the left and right sides of the bale respectively) areadjusted to have greater loop length, but the next most outer twineloops (say the second and fourth loops referring to FIG. 2) could alsobe adjusted, perhaps to a lesser extent. Of course the same principlecould be applied to balers with more than 3 twine loops.

Although the description is based on a double tie knotter (knotting twoknots 40 and 40′ in the loop) the principle of adjustment of the twineloop length will also be effective on a single tie knotter baler (withonly knot 40′ in the loop).

1-16. (canceled) 17: A baler apparatus comprising: a baling chamberincluding a channel including an inlet end and an outlet end and atleast one adjustable wall adjusting compression of a body of balematerial by controlling pressure applied to the body of bale materialduring formation of a bale; a reciprocating plunger adjacent the inletend of the baling chamber operable to compress a body of bale materialwithin the baling chamber; a binding device binding the compressed bodyof bale material to form a bale by use of twine loops; and an extensiondevice extending a length of outermost twine loops at binding of thebale, compared to innermost twines, to reduce compression within anouter part of the body of bale material. 18: The baler apparatus ofclaim 17, wherein the extension device extends twine loop length inresponse to factors including type of bale material and environmentalconditions. 19: The baler apparatus of claim 17, wherein the extensiondevice includes a roller or guide. 20: The baler apparatus of claim 19,wherein the roller or guide is locatable for engagement against anoutside of the twine loop. 21: The baler apparatus of claim 17, furthercomprising a twine guide guiding the twine over the roller or guide. 22:The baler apparatus of claim 19, wherein the roller or guide is locatedadjacent a knotting device. 23: The baler apparatus of claim 17, whereinthe binding device is configured to close the twine loop with one singleknot. 24: The baler apparatus of claim 17, wherein the binding device isconfigured to close the twine loop with two knots. 25: The balerapparatus of claim 17, wherein the extension device is configured toindependently vary a length of individual twine loops per twine loop.26: The baler apparatus of claim 17, wherein an extra loop lengthincrease of outermost twines is 1-3 cm relative to innermost twines. 27:The baler apparatus of claim 17, wherein the extension device alsoincreases second outermost twines by 1-2 cm relative to innermosttwines. 28: The baler apparatus of claim 17, wherein the extensiondevice is configured to increase loop length of a twine by up to 25 cmfrom its regular length. 29: The baler apparatus of claim 17, whereinthe extension device is easily removable or displaceable. 30: The balerapparatus of claim 17, wherein the extension device is fixedly butadjustably connected to the baler. 31: The baler apparatus of claim 17,wherein the increase of the loop length is achieved by positioning aknotting device relatively further or at an adjustable distance from thebale when the twine loop is formed. 32: A method of baling bale materialin a baler apparatus including a baling chamber including a channelincluding an inlet end and an outlet end, a reciprocating plungeradjacent the inlet end of the baling chamber, and a binding device, themethod comprising: activating the reciprocating plunger to compress abody of bale material in the baling chamber, wherein outermost twineloops are lengthened relative to innermost twin loops around balematerial, at least during closing of a loop, to form a bale.